const leet = new Map();
leet.set('id0',0)
leet.set('id',1)
leet.set('id2',2)
leet.set('id3',3)

const value = leet.keys().next().value
console.log(value);
console.log(leet);
console.log(leet.values() instanceof Object);
console.log(leet.values instanceof Function);
console.log(typeof leet.values === 'function'); // function , object 具体的方法